Energy from the water cycle: a promising combination to operate climate neutral

Waternet, the first water cycle company in the Netherlands, is responsible for drinking water treatment and distribution, wastewater collection and treatment, and water system management and control in and around Amsterdam. Waternet has the ambition to become climate neutral in 2020. To realise this ambition, measures are required to compensate for the emission of 53,000 t CO2-eq/year. Energy recovery from the water cycle looks very promising. From wastewater, ground water, surface water and drinking water, all elements of the water cycle, renewable energy can be recovered. This can be thermal energy and chemical energy. First calculations reveal that energy recovery from the water cycle in and around Amsterdam can contribute to a total reduction in greenhouse gas emissions up to 74,900 t CO2-eq/year. The challenge for the coming years is to choose robust combinations of all the possibilities to fulfil the energy demand at any time. Only then can the use of fossil fuel be abandoned and the target of becoming climate neutral in 2020 be reached.

Climate change mitigation by recovery of energy from the water cycle: a new challenge for water management

Greenhouse gas (GHG) emissions contribute to climate change. The public water utility of Amsterdam wants to operate climate neutrally in 2020 to reduce its GHG emissions. Energy recovery from the water cycle has a large potential to contribute to this goal: the recovered energy is an alternative for fossil fuel and thus contributes to the reduction of GHG emissions. One of the options concerns thermal energy recovery from drinking water. In Amsterdam, drinking water is produced from surface water, resulting in high drinking water temperatures in summer and low drinking water temperatures in winter. This makes it possible to apply both cold recovery and heat recovery from drinking water. For a specific case, the effects of cold recovery from drinking water were analyzed on three decisive criteria: the effect on the GHG emissions, the financial implications, and the effect on the microbiological drinking water quality. It is shown that cold recovery from drinking water results in a 90% reduction of GHG emissions, and that it has a positive financial business case: Total Cost of Ownership reduced with 17%. The microbial drinking water quality is not affected, but biofilm formation in the drinking water pipes increased after cold recovery.

Major US electric utility climate pledges have the potential to collectively reduce power sector emissions by one-third

This study presents a baseline assessment of carbon emissions in water utilities in Madaba, Jordan. The Energy Performance and Carbon Emissions Assessment and Monitoring Tool (ECAM) is applied in the present study in order to reduce indirect and direct emissions. Input data for the assessment included inter alia, population, water volumes, energy consumption, and type of wastewater treatment. The methodology focuses on the greenhouse gas (GHG) emissions and energy use that is directly associated with the utility operations covering the whole water cycle. The ECAM's Quick Assessment revealed that 89.7% of the energy is consumed in abstraction and distribution systems of water supply, whereas wastewater collection, treatment, and discharge consumed only 10.3% in Madaba. The detailed ECAM tool assessment results showed that total GHG emissions from the entire water and wastewater system in Madaba are approximately 28.122 million kg CO2/year. The water supply is the major contributor to GHG accounting for 62.4%, while 37.6% of GHG emissions result from sewage treatment, and are associated with treatment process requirements considered in this work, in addition to sludge transport from septic tanks to the wastewater treatment plant. The findings of this work can help the utility to undertake energy efficiency and GHG reduction measures.

Imposing versus Enacting Commitments for the Long‐Term Energy Transition: Perspectives from the Firm

In August 1999, the U.S. Global Change Research Program (USGCRP) appointed a Water Cycle Study Group (WCSG) to advise the USGCRP agencies on the development of a Global Water Cycle Program. The charge to the WCSG was to define a USGCRP initiative for fiscal years 2001 and beyond. After more than a year of work, which included soliciting views from the broad community of scientists and engineers interested in water cycle research, the WCSG issued its report in 2001 (http://www.usgcrp.gov/usgcrp/Library/watercycle/wcsgreport2001/default.htm). The report describes the rationale for research intended to provide critical fundamental knowledge about the water cycle—the amount of water in various reservoirs, the fluxes among these reservoirs, and the role of the changing amounts and fluxes in climate dynamics. Such research will provide information and tools to improve the use of water resources and to reduce losses associated with hydrologic extremes. The details of a research agenda to improve knowledge about the water cycle are necessarily involved. The major questions guiding such research can be stated quite succinctly, however. First, how much water of what quality is available, and how have these measurements of quantity and quality changed over time? The ability to assess the resource depends critically on knowing the amount of water in each water cycle component, how much water is moving among the components, the quality of water, and how amounts and quality have changed over time. Second, how are amounts and quality of water in various water cycle components likely to change in the future—over the next few days in response to weather, over the next few months in response to seasonal change, and over longer times in response to changes in water use, climate, and land use and land cover? Answering these deceptively simple questions will require dedicated work by scientists from a range of earth science disciplines, including hydrogeology, geochemistry, and geophysics. The water cycle research agenda is not restricted to the role of surface and near-surface water on climate. To be sure, more work on land-atmosphere linkages and feedbacks influenced by surface water and soil moisture is needed to understand the climate system. But ground water is the largest reservoir of liquid fresh water on the earth and is certain to become ever more important as a resource. Demand for fresh water is steadily increasing, and at the same time, the overall quality of water for humans and ecosystems is decreasing because of pollution and other human-imposed stresses. The pressure to use ground water will continue to increase, and if the resource is to be used wisely and sustainably, ground water scientists will have to be active participants in water cycle research. The status of our knowledge of ground water components of the global water cycle is not good. We hardly have enough data to determine amounts of stored water for critical and overstressed aquifers in the United States, let alone internationally. Sustainable use of ground water resources demands knowledge of recharge and discharge, fluxes for which adequate measurement techniques are not available in many instances. It is precisely these recharge-discharge processes that must be the focus of a major water cycle research initiative related to ground water (e.g., National Research Council. 2004. Groundwater Fluxes across Interfaces. Washington, D.C.: National Academy Press). Data and information with enhanced resolution and increased precision relative to that collected in the past must be developed. Techniques borrowed from neighboring disciplines must be adapted to provide new methods for measuring key variables. Data from new sensors and from existing networks will have to be integrated, and new observation networks will have to be established. Existing long-term records must be archived and preserved, and observations must be continued indefinitely at sites with long high-quality records, so that patterns of temporal variability, including long-term, low-frequency fluctuations, can be identified and studied. All of the measurements—at various scales—will have to be interpreted within the context of conceptual models and their mathematical implementations. Ultimately these models must evolve so that reliable predictions of responses to stresses in the future can be made. To improve predictions, a comprehensive program that includes observations, field experiments, and numerical modeling will be needed. The challenges of these research efforts for ground water scientists are formidable. But it is essential that the challenges be met. The rewards associated with gaining improved understanding are obvious. So are the penalties for failing to do so.

Urban water cycle systems(UWCS), including water treatment facilities, distribution facilities, sewers, and wastewater treatment facilities, are energy intensive and significant source of greenhouse gas (GHG) emissions, making the reduction of GHG emissions and the transition to eco-friendly energy essential. This study identifies specific GHG emission sources at each stage of the UWCS and proposes detailed methods to achieve a 40% reduction in GHG emissions, implement RE100, and attain Net Zero by employing insets and offsets. This study develops scenarios for insets and offsets based on the baseline process of the UWCS, and investigates potential pathways to reduce GHG emissions by quantifying emissions from each process. Internal insets, which are self-implemented and technical measures, are prioritized, while external offsets are applied to compensate for the remaining emissions. Internal insets include the application of anaerobic digesters and combined heat and power(CHP), improvements in energy efficiency of equipment, reduction in water pipe leakage, implementation of water footprint labeling, and installation of on-site photovoltaic system. External offsets comprise renewable energy certificates(REC), power purchase agreements(PPA), green hydrogen fuel for vehicles, natural sequestration improvement, and emission trading system. GHG emissions at each stage within the UWCS are quantified using modeling software. Based on these results, the effectiveness of insets and offsets in achieving a 40% GHG emissions reduction, Net Zero, and RE100 goal is analyzed. The baseline total GHG emissions for the UWCS are estimated at 4,732.8 tCO2eq/yr, of which 56.8% is identified as targets for internal insets, and the remaining 43.2% is reduced through external offsets. A 40% GHG reduction can be achieved through internal insets, and Net Zero can be attained by incorporating additionally applying external offsets. The total power demand of UWCS facilities and equipment is calculated as 572.8 kW. Renewable energy is generated through anaerobic digesters and CHP(116.1kW) as well as on-site PV(395.0 kW), while RE100 compliance is achieved by securing an aditional 61.7 kW through REC/PPA. Achieving Net Zero and RE100 requires prioritizing strategies for insets, offsets and efficient resource allocation. For this, the technical feasibility and self-implementation potential of reduction efforts and the external conditions for offsets, should be carefully reviewed to optimize implementation strategies. GHG reduction and renewable energy utilization in the UWCS are key priorities for addressing the climate crisis and achieving sustainable water resource management, requiring technological innovation and institutional support. The comprehensive and systematic application of GHG insets and offsets is the optimal approach to achieving these goals. Furthermore, modeling software serves as a key tool for quantifying GHG emissions and formulating concrete, viable GHG reduction strategies. In addition to the technical and institutional approaches proposed in this study, achieving Net Zero and implementing RE100 requires the integrated consideration of economic factors in the future.

Mitigating Curtailment and Carbon Emissions through Load Migration between Data Centers

As part of the Net Zero Carbon Water Cycle Program (NZCWCP) for Victoria state in Australia, we have sought to understand the potential to reduce household energy consumption and related Greenhouse Gas (GHG) emissions by influencing water use. Digital metering data disaggregated into 57 million discrete water usage events across 105 households at a resolution of 10 millilitres at 10 second intervals from June 2017 to March 2020, from a previous Yarra Valley Water (Melbourne, Australia) study, was analysed, together with the dynamic relationship between the multiple energy sources (natural gas, grid electricity, solar) used to heat water for showers in each hour of the day. Water-related energy (WRE) use, including water desalination and treatment, pumping, heating, wastewater collection and treatment, comprised 12.6% of Australia’s primary energy use in 2019. Water heating (by natural gas and electricity) comprised the largest component of WRE use for across residential, commercial, and industrial sectors. Furthermore, 69% of Victoria’s total water usage was by residential customers in 2020-2021. WRE GHG emissions were around 3.8% of Victoria’s total GHG emissions in 2018. Showers (~50% of residential WRE), system losses (~27% of residential WRE), and clothes washers (~9% of residential WRE) are the three largest components of WRE consumption. The main objective of this work is the creation of industry-accessible tools to improve knowledge and management options from the understanding of reductions in cost and GHG emissions from household showering WRE use. Potential options considered, to reduce water and energy use, as well as associated GHG emissions and customer utility bills, include (a) behaviour management such as water and energy pricing to change time of use behaviours, and (b) the adoption of efficient shower head improvements. Shower WRE and GHG emissions were found able to be strongly impacted by small changes in daily routines. GHG emissions reduction from showering could be reduced up to 20 (in summer) - 22% (in winter) by shifting demand time of showering or replacing residential showerheads. Extrapolated to state and Australian scales, reductions in water usage could be up to 14 GL (Victoria) and 144 GL (Australia), and reductions in GHG emissions 1,600 ktCO2eq (Victoria) and 17,300 ktCO2eq (Australia). It provides fundamental new information which could inform a suite of new management options to impact water-related energy from showers, and related GHG emissions and customer water and energy cost.

Understanding the greenhouse gas emissions from China’s wastewater treatment plants: Based on life cycle assessment coupled with statistical data

At present, urban greenhouse gas (GHG) emissions from different wastewater treatment stages are attracting increasing attention. Based on the Guidelines of the China Greenhouse Gas List Compilation (Trial) and the IPCC National Greenhouse Gas List Guidelines in 2006, this paper evaluated urban GHG emissions from wastewater treatment in China from 2011 to 2020. The contribution rates of GHG emissions to the total GHG emissions were calculated for the different wastewater treatment stages. The variations in annual GHG emissions and differences in GHG emissions among different regions and provinces were also analyzed. The total amount of equivalent CO2 emissions reaches 1478.51 million tons, and the annual average amount of equivalent CO2 emissions from 2011 to 2020 is 147.9 million tons, which shows a trend of decreasing first and then increasing. The distribution of GHG emissions from wastewater treatment is uneven among provinces and regions; Guangdong Province has the highest emission, while the Xizang autonomous Region has the lowest. The correlation and contribution rate analysis revealed that paper production and chemical and side food production could discharge a large amount of wastewater with a high COD content, which may have an important impact on GHG emissions during the wastewater treatment stages. According to the study results, CH4 accounts for the largest proportion (63.08%) of the total GHG emissions. The most important source of CH4 comes from the industrial wastewater treatment stage. The annual average CO2 emissions account for 22.24% of the total GHG emissions, which are mainly from the power and chemical consumption stage. The annual average N2O emissions account for 14.68% of the total GHG emissions and are mainly from the wastewater collection and discharge stage. Therefore, in the future, GHG emission reduction strategies should focus on CH4 emissions in the industrial wastewater treatment stage and develop CH4 recycling and utilization technologies.

Greenhouse gas (GHG) emissions reduction in the electricity sector: Implications of increasing renewable energy penetration in Ghana's electricity generation mix

Water Accounting Plus for Water Resources Reporting and River Basin Planning

With their increasing shares of global emissions developing economies are increasingly being pressured to assume a greater role in global greenhouse gas (GHG) emission reduction. Developed countries have invested tremendously in and proclaimed renewable energy (RE) and associated smart power technologies as solutions to meet their energy demands and reduce their GHG emissions at the same time. However, in the developing economies, these technologies may not deliver the desired results because they have their unique characteristics and priorities, which are different from those of the developed world. Many GHG emission reduction technologies are still very expensive and not fully developed. For the developing economies, the adoption threshold may become very high. Therefore, the cost effectiveness and practicality of each technology in reducing GHG emission in the developing economies may be very different from that of the developed economies. In this paper, available RE and other GHG emission reduction technologies are individually considered in a case study on Sabah, one of the 13 states in Malaysia, in order to assess the effects of the individual technologies on GHG emission and electricity cost reductions.